Time to First Paint
Time to First Paint, also referred to as Time to Start Render, is a timing metric used in measuring web page loading speed. It refers to the time duration from when a web page URL is entered into a browser window to the moment when the user sees the first visual element of the web page in the browser window.
"Time to First Paint" is a key milestone for web page loading. Before Time to First Paint, the user is looking at a blank browser screen. This is the duration during which users most likely to abandon the site. So it is crucial for web sites to minimize "Time to First Paint".